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When to throw an exception?
...a function which is supposed to examine an arbitrary class and return true if that class inherits from List<>. This function asks the question, "Is this object a descendant of List?" This function should never throw an exception, because there are no gray areas in its operation - every single ...
Check if current directory is a Git repository
...rg.uk/).
# Distributed under the GNU General Public License, version 2.0.
if [ -d .git ]; then
echo .git;
else
git rev-parse --git-dir 2> /dev/null;
fi;
You could either wrap that in a function or use it in a script.
Condensed into a one line condition suitable for bash and zsh
[ -d .git...
Quick-and-dirty way to ensure only one instance of a shell script is running at a time
...that uses a lockfile and echoes a PID into it. This serves as a protection if the process is killed before removing the pidfile:
LOCKFILE=/tmp/lock.txt
if [ -e ${LOCKFILE} ] && kill -0 `cat ${LOCKFILE}`; then
echo "already running"
exit
fi
# make sure the lockfile is removed when w...
How to do if-else in Thymeleaf?
What's the best way to do a simple if - else in Thymeleaf?
10 Answers
10
...
Return type of '?:' (ternary conditional operator)
...alue or an rvalue. This is its value category. (This is somewhat of a simplification, in C++11 we have lvalues, xvalues and prvalues.)
In very broad and simple terms, an lvalue refers to an object in memory and an rvalue is just a value that may not necessarily be attached to an object in memory.
An...
Find an element in a list of tuples
...
If you just want the first number to match you can do it like this:
[item for item in a if item[0] == 1]
If you are just searching for tuples with 1 in them:
[item for item in a if 1 in item]
...
I want to remove double quotes from a String
...console.log(someStr.replace(/['"]+/g, ''));
That should do the trick... (if your goal is to replace all double quotes).
Here's how it works:
['"] is a character class, matches both single and double quotes. you can replace this with " to only match double quotes.
+: one or more quotes, chars, a...
Delete all but the most recent X files in bash
...d globbing.
inability to distinguish between files and directories (i.e., if directories happened to be among the 5 most recently modified filesystem items, you'd effectively retain fewer than 5 files, and applying rm to directories will fail).
wnoise's answer addresses these issues, but the solu...
How to detect the currently pressed key?
...
if ((Control.ModifierKeys & Keys.Shift) != 0)
This will also be true if Ctrl+Shift is down. If you want to check whether Shift alone is pressed,
if (Control.ModifierKeys == Keys.Shift)
If you're in a class that inh...
Determine whether JSON is a JSONObject or JSONArray
...ich it will be. I need to work with the JSON, but to do so, I need to know if it is an Object or an Array.
8 Answers
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